This invention generally relates a system including electrical actuators for changing gears within a vehicle transmission range gear box.
Heavy duty vehicle transmissions typically provide the ability to engage a large number of gear ratios for driving the vehicle. In many instances, a main transmission gear box houses a number of gear members that are selectively engaged to choose a particular gear ratio. An auxiliary or range gear box is often also provided to increase the number of available gear ratios. The range gear box typically includes one or more range gear members that are selectively engaged to operate the transmission in one of several ranges. A first range is typically associated with a number of lower gears such as a first gear through fifth gear, for example. When the range box is shifted into high range, then the same gears in the main gearbox that were used for first through fifth gear are now used for sixth through tenth gear, for example.
Pneumatic shift actuators generally have been used to effect a change of gears in the range gear box. Currently available pneumatic components shifting actuators include several shortcomings and drawbacks. A number of the pneumatic components associated with such systems are prone to contamination and are susceptible to developing air leaks. Such contamination or air leaks render the system inoperative or place it in a condition of poor performance, which requires repair or replacement.
Further, pneumatic components can be too slow under some circumstances. For example, when shifting into the high range, under some circumstances it is possible for the driver to complete the shift in the main gear box and begin to accelerate the vehicle before the range gear is fully engaged. This sequence of events is known in the art as "beating the range shift" and introduces the possibility for undesirable wear or damage to the transmission components.
This invention recognizes the problems and shortcomings associated with conventional transmission systems and provides an improved system. This invention provides a transmission control system that eliminates the need for some of the conventional components, which are subject to failure as discussed above, and utilizes an efficient system that is readily adapted to most heavy duty vehicle transmissions.